US 2007/0109784 A1 discloses a lighting apparatus comprising a laser emitting a laser beam being expanded by a negative lens and collimated by a positive lens. The expanded collimated light beam is directed onto a transmissive holographic diffuser to produce a diffused light beam. The diffused light beam has an expanded cross section and provides an extended glare source at increased power downrange. The extended source produced by the holographic diffuser creates an extended image on the retina of the human eye. The extended retinal image permits a higher power laser exposure, compared to a point source image common in conventional designs.
This lighting apparatus has the drawback that, if the holographic diffuser of the lighting apparatus is damaged, the dimensions of the image on the retina can be varied, in particular, reduced. This could lead to an increased intensity on the retina and, thus, to an increased risk of damaging the retina.